Installation of photovoltaic panels, has been on the rise.
There are two types of installation of photovoltaic panels on a roof:                photovoltaic panels to be laid superimposed on a roof;        photovoltaic panels fixed to roof surfaces instead of the normal roof material, or in combination therewith.        
When the panels are intended to be placed superimposed on a roof, they are generally mounted in a frame, for example made from aluminium, the latter being intended to be fixed to the roof in various ways, such as:                shoes for a corrugated iron roof;        bolts for fixing to metal rings;        clips for fixing to a zinc roof;        hooks for fixing to roof tiles;        other known attachment systems.        
For panels intended to be fixed in place of normal roof material, the panels are also mounted in a frame, the latter being intended to be mounted directly on the roof timbers, for example by means of rails. In this case, mounting the panel involves using a relatively large amount of hardware, such as fixing shoes, rails, flashing, beads, gaskets, fillets, edge strips, and a whole range of associated screws.
It will be appreciated that mounting photovoltaic panels on a roof involves the use of numerous fixing parts, and requires recourse to specialized trades.
In addition, conventional techniques associate the panels with a metal frame, composed of profiles. However, producing such frames proves relatively expensive, all the more so since it is often necessary to provide different profiles according to the dimensions and/or design of the photovoltaic panels.
Moreover, the assembly formed by the photovoltaic panel and the metal frame has considerable weight, which tends to be detrimental to the ease of handling the assembly, in particular during operations of mounting on the roof. As specified previously, in the present description, the expression “photovoltaic panel” designates the panel as such, without the frame. A photovoltaic panel conventionally includes a film of photovoltaic cells between two support plates, for example made from glass.
Moreover, current techniques usually neglect an important parameter having impact on the optimised functioning and long life of the photovoltaic panels, with regard to the heating of the cells that make them up. This is because excessive heating of the panel gives rise to a risk of damage to this photovoltaic cells and/or a reduction in the efficiency thereof. However, by nature, these panels are exposed to sunshine liable to generate strong heat at the roofs on which the photovoltaic panels are mounted.